You’ve probably heard at least once in your life that the Great Wall of China is the only man-made object that can be seen from space. Is this true though? What about the pyramids or the great cities that have skyscrapers that reach into the clouds?
The Great Wall of China is not visible to the naked eye from space, including low-earth orbit. The Wall, however, can be imaged from the International Space Station using a digital camera with magnification on a clear day. Once you travel further into space, say as far as the moon, no man-made object can be observed with our current technology.
So, where did the myth that the Great Wall of China could be seen from space originate? Why is it still believed today despite being refuted by science? What evidence is there to completely demolish the myth once and for all?
Where Did the Myth Begin?
The declaration that you can see the Great Wall of China from space has been perpetrated since at least 1754 when William Stukeley claimed this in a letter. However, the popularity of the myth didn’t enter the general consciousness until the 1900s. Decades before mankind’s first satellite, Sputnik, orbited the earth in 1957 or Yuri Gagarin became the first man in space in 1961, two novels claimed The Great Wall was visible from space.
“Besides its age [the Great Wall of China] enjoys the reputation of being the only work of human hands on the globe visible from the moon.”Henry Norman, The People and the Politics of the Far East, 1904.
“Astronomers say that the Great Wall is the only man-made thing on our planet visible to the human eye from the moon.”Richard Halliburton, Second Book of Marvels – The Orient, 1938.
Despite a lack of scientific evidence, the Great Wall of China’s size and length added credibility to these claims. The wall itself is 5,500 miles long, with nearly 4,000 miles of that being a physical wall (the rest is trenches and natural barriers such as rivers and hills). To the pre-space age human, it seemed perfectly plausible that this mammoth structure could be seen from high above the Earth’s surface.
The Moon is Too Far Away. How Close Do You Need to Be?
After the Apollo missions took explorers far into space and sent back images of the Earth’s horizon from the moon, everyone saw how inconsequential mankind’s structures are at that scale.
“No man-made object is visible at this scale.”Alan Bean, Apollo 12 astronaut.
With our satellite being 238,900 miles away from Earth, all Apollo astronauts reported seeing was a mass of blue, clouds, and a touch of green. There was no possibility of picking out the Great Wall or any other man-made object for that matter.
Norberto López-Gil, a professor in optics, wrote in 2003 that you would need to have “a visual acuity 17,000 times better than the human eye” to see the Great Wall from the moon. hat about the International Space Station (ISS) that orbits the earth at a distance of 245 miles? It’s still too far according to Dr. López-Gil. He noted that even in low orbit [like the ISS], your vision would need to be 3.9 times better than the average human to see the Great Wall.
Indeed, once you are roughly 25 miles high, it becomes impossible to observe The Great Wall of China with the human eye alone. Even within this minimal range, the Great Wall can be difficult to distinguish from the landscape it sits among. That is because the Wall is made from local natural resources. Therefore, the color of the Great Wall blends easily into its background when viewed from above.
Why Do People Still Believe in the Myth?
Despite every astronaut testifying that you couldn’t see the Great Wall of China from Space since the 50’s, the Chinese thought it was a political conspiracy against their country. China used propaganda for 50 years to elevate the belief, knowing that it increased their nation’s status in terms of power, size, and strength. It was written in textbooks and was seen as a national symbol of pride.
It wouldn’t be until 2003 when the first Chinese astronaut Yang Liwei confirmed that it couldn’t be seen from the ISS, that the Chinese population began to accept that the claim wasn’t true. It shocked the nation and Liwei received threats from patriots for reducing the perceived strength of Chinese.
Just as the fallacy began to die down, pictures emerged from the ISS in 2004, that revitalized the belief. American-Chinese astronaut, Leroy Chiao, took the first official photograph of the Great Wall of China from space, using a 180 mm lens. He took another using a 400 mm lens in 2005. These images circulated with rejoiceful vigor throughout China. Controversially, Chiao stated he didn’t see the wall and wasn’t convinced that the picture showed it.
NASA themselves defended the Chinese media’s view of the images – they showed a small portion of the constructed wall. The image was only possible because it was a clear day, it had snowed recently to make the wall stand out from its usual camouflaging background.
Even though the Chinese took the endorsement as a victory, it must be noted that the 180 mm lens used is far more powerful than the human eye. Even with this official, annotated picture from NASA, few can really be certain that the Great Wall of China is really what it shows.
This photo of central Inner Mongolia, about 200 miles north of Beijing, was taken on Nov. 24, 2004, from the International Space Station. The yellow arrow points to an estimated location of 42.5N 117.4E where the wall is visible. The red arrows point to other visible sections of the wall. Credit: NASA.
As technology improves, so will the magnification and resolution of the images we can take of our earth from low Earth orbit. Until then, images like the one above are as clear as the Great Wall will be.
Whether you can see the Great Wall of China from space is dependent on two things:
- What is your definition of space
- Can you use imaging techniques other than the human eye to see it
What is proven though, is that the human eye cannot see the Great Wall alone from low Earth orbit.
What Man-made Objects Can Be Seen from the ISS?
A remarkable number of man-made objects can be seen from the ISS. The pyramids at Giza are easily spotted as are large cities, especially at night. Roads are easily observable as they tend to be straight lines drawn on the landscape and, therefore, stand out.
Where Does Space Begin?
Space treaties define space beginning at the Kármán line, which is lies at 100 km (62 mi) above sea level. This is the point where Earth’s atmosphere ends. It was named after Theodore Kármán, a Hungarian-American engineer and physicist. There is not a definition of “outer space”.